Manual PCB inspection
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This slide deck takes you through important elements of manula PCB inspection including some definitions, what makes a good inspector , what type of lighting is required to be able to see the important aspects of a PCB and the types of inspection aids. The slide deck ends with some real examples where the user is challenged to make a determination of defect/process indicator/acceptable of an electronics assembly in accordance with the IPC-A-610 and IPC-A-620 standards.
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Manual PCB inspection
- 1. Business Electronics Soldering Technolo Manual Inspection of PCBs Bob Wettermann
- 2. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 I. Introduction II. Attributes of a good inspector III. Lighting for inspection IV. Inspection aids V. Inspection of PCBs – Some practical examples Inspection of PCBs Strategies
- 3. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 The process of using an unaided eye, alone or in conjunction with various aids, as the sensing mechanism from which judgements may be made about the condition of a unit to be inspected. FAA AC-43-204 Inspection of PCBs Strategies Manual Process Inspection Definition
- 4. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Inspection of PCBs Strategies Probability of Detection vs Size of Anomaly The applicability of reliability-based inspection planning for steel bridges based on fatigue crack detection John Leander August 2017 Conference on Bridge Assessment
- 5. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 • Spot checks on the production floor for high volume • Prototype inspection • New process inspection • Areas where automated inspection cannot or has a hard time accessing Inspection of PCBs Strategies Manual Inspection-Where is its Place?
- 6. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 • Visual inspection accuracy is 80% (Juran calculated 100% inspection is about 87% effective) • Reasonable complex as parts are different sizes, shapes and density and there are lots of chances to impact the DPMO Inspection of PCBs Strategies Manual Inspection-Where is its Place?
- 7. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Type of Inspection in Manufacturing A. Preproduction Inspection B. During Production Inspection C. Final Random Inspection D. Container Loading inspection Inspection of PCBs Strategies
- 8. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 1.10 The tolerance for magnification aids is +/- 15% of the selected magnification power. Magnification aids, if used for inspection shall be appropriate with the item being inspected. Unless magnification requirements are otherwise specified by contractual documentation tables shall determine the magnification. Inspection of PCBs Strategies Magnification Aids Reference: IPC-A-610 Rev G
- 9. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Manual Inspection of PCBs Aids Tri-ocular Digital Stereo Ring Lamp
- 10. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Inspection of PCBs Strategies Magnification Aids Land Widths of Land Diameters Inspection Range Maximum Referee >1mm 1.5 to 3x 4x >0.5 to <=1mm 3 to 7.5x 10x >=0.25 to <=0.5mm 7.5 to 10x 20x <0.25mm 20x 40x Reference: IPC-A-610 Rev G
- 11. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Inspection of PCBs Strategies Magnification Aids Land Widths of Land Diameters Inspection Range Cleanliness (with or without cleaning processes) Magnification not required. See (A-below) Cleanliness (no-clean processes) Magnification not required. Visual inspection may require the use of magnification such as when fine pitch or high density assemblies are present magnification may be needed to determine if contamination affects form , fit or function (A) Conformal Coating (A-above) , If magnification is used it is limited to 4x maximum Marking If magnification is used it is limited to 4x maximum Other (Component and wire damage) (A-above) Reference: IPC-A-610 Rev G
- 12. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 1.11 Lighting shall be adequate for the item being inspected Illumination at the surface of the workstations should be at least 1000lm/m2 (93 ft candles approx). Light sources should be selected to prevent shadows Note: I selecting a light source the color temperature of the light is an important consideration. Light ranges from 3000-5000 °K enable users to distinguish various printed circuit assembly features and contaminated with increased clarity. Inspection of PCBs Strategies Lighting for Inspection Reference: IPC-A-610 Rev G
- 13. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Inspection of PCBs Strategies Lighting Methods Back Lighting
- 14. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Inspection of PCBs Strategies Lighting Methods Front Lighting Front Lighting
- 15. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Examples to follow of inspection examples to IPC-A610 and IPC-A-620 Class 2 Example Inspection
- 16. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 17. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 18. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 19. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 20. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 21. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 22. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 23. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 24. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 25. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018
- 26. Your BEST choice in PCB Rework/Repair, Solder Training & Tools Copywrite BEST Inc 2018 Bob Wettermann bwet@solder.net MIT BEST Inc
Notas do Editor
- Not covering anything to do with other NON DESTRUCT mechanicsms like x-ray or AOI….just eyeballs aided Level 1 Walkaround-general check and general condition Level 2 General General inspection of a larger area usually to detect damage , failure or irregularity Level 3 Detailed. Intensive visual inspection/examination of a specific area, system or assembly to detect an irregularity. Sometines with inspection aids Level 4 Special detailed, Intensive nd una idedexamination of specific item to detect damage, failure or irregularity Usually specific techniques and equipment AGAIN FAA
- Probability of Detection graph Panhuise and other reseearchers have maintained that the ideal detection system would have a step function POD; zero detection below threshold and perfect detection above the threshold low mean and lpow variability is the perfect scenario
- Throughhole parts for wetting Flux residue Conformal Coating
- Throughhole parts for wetting Flux residue Conformal Coating
- stereo microscopes give the viewer an erect (upright and un-reversed) stereoscopic (3-dimensional) image While also allowing the object (PCB) to be handled in the field of view
- Back lighting ideal for go/no go and measurement of obkjects as contrast may be more easily seen
- Light source and product on same side of a product Higher angle of incidence can use the shadows to determone the heoghts on the board
- IPC 620 Coax cable defect for excessive strand damage 620
- Dpak defect for no heel fillets on gull wing leads and less than 100% wetting of thermal tab to pad contact area D Pak: Defect , no heel fillet IAW para. 8.3.5.6
- Skyworks module acceptable Flat lug lead on right top defective for insufficient solder for side joint and end joint Slide 3 Flat Lug lead : Defect , insufficient side joint length on top two leads possible non wetting on right side bottom lead but bad lighting and angle of pic. Para 8-3.9
- Transformer/Choke defective for damage to body Slide 4 transformer: defect, cracked, burned para 9.3
- U7 Acceptable Slide 5 SOIC Gull wing lead: bad picture angle to inspect would have to assume.
- Solder charged termination defective for coplanarity and missing solder connections Slide 6 Solder Charged Terminations: defect, IAW para 8.3 tilted.
- Cracked Ceramic package Slide 8 LED: defect, cracked end 9.3
- Connector charred defect for damage to body on left side Slide 9 Connector: acceptable, Slight melting as long as it meets form fit and function para 9.5
- Yellow wire defective for lead to barrel wetting Slide 10 Thru hole wires: defect, non wetting 5.2.4
- Acceptable Also inspect same distance form the board instead of “looking down the barrel” This is a big deal when photographing or when at PTHs